Perhaps the most important feature is the CLOCK. This is fitted to enable the time at which the transmitter is switched on to be preset within the limits 0-48 hours (see clock face dial). In addition to switching the transmitter on it also provides automatic keying of the transmitter. A special 'code letter' is transmitted, the 'code letter' being determined by a small cam which can be interchanged at will. Six cams are provided which give a DASH of approximately 7 seconds duration when a standard clock is used. In a large number of sets the clock mechanism has been slowed down, giving the length of "homing" dash approximately 11 to 13 seconds. The length of a DOT in Morse code becomes in this case, 1 second approximately and the length of a DASH in Morse code 3 seconds approximately. The set of code cams contains the following 'code letters' : A, B, D, N, U and V. Thus, assuming that a 'mission' has been assigned the 'code letter' U, the automatically transmitted signal is:- DOT DOT DASH HOMING SIGNAL followed by a four seconds before the signal repeats itself. This is a total of:-

(c) Automatically. Wind the clock up fully. Set the dial on the shaft so that the starting lever is pointing to zero. The adjustment pointer (trip lever) should be set so that the following or longer edge indicates the desired time of the start of transmission. In the drawing of the clock above, you will see that it has been set to start transmitting 6 HOURS after setting, namely the longest edge of the trip lever is on figure 6.

The length of time the transmitter will send the homing signal, assuming the batteries are new, is FOUR HOURS. However, if a long time is known to be required, either two separate sets should be deployed, or a shift to manual Morse should be contemplated, sending the homing signal say, for five minutes every half hour. DOT DOT DASH 12 SECONDS HOMING DASH

The signal emitted is MCW so that any receiver can demodulate its signal.